In the catalytic hydroprocessing of hydrocarbon feedstocks, such as crude oil, distillates and residual crude oil fractions, catalyst compositions containing hydrogenation metals are used to promote desulfurization and denitrogenation reactions and thereby provide for the removal of organic sulfur and organic nitrogen compounds from the hydrocarbon feedstocks. The processes involve contacting catalyst particles with a hydrocarbon feedstock under conditions of elevated temperature and pressure and in the presence of hydrogen to convert sulfur components of the feedstock to hydrogen sulfide and nitrogen components of the feedstock to ammonia. The hydrogen sulfide and ammonia subsequently are removed to give the hydrotreated product.
Hydrotreating catalysts comprise hydrogenation metal components on a refractory oxide. The hydrogenation metal components are generally Group VI metal components such as molybdenum and/or tungsten and Group VIII metal components such as nickel and/or cobalt. The porous refractory oxide support material can typically be alumina. Promoters such as phosphorus may also be used as a component of the hydroprocessing catalyst.
There is a continuous interest in further improving the performance of these catalysts.
A method which can lead to improved performance is treating a carrier with a solution containing catalytically active metal and an organic ligand and subsequently drying the treated carrier. By not calcining such dried catalyst, an improved performance can be attained as mentioned in publications such as EP-A-0482818, WO-A-96/41848, WO 2009/020913 and WO 2012/021389. The preparation of catalysts which are only dried but not calcined is relatively complex and cumbersome in actual commercial practice.
The aim of the present invention is to find a process which is relatively easy to apply while providing a hydrotreating catalyst having good activity in the manufacture of low sulphur and nitrogen fuels such as ultra low sulphur diesels.